JPS581714B2 - Heat storage agent composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage agent composition containing calcium chloride hexahydrate as a main ingredient.

Generally, methods for storing heat include methods that utilize the sensible heat of substances and methods that utilize latent heat.

A typical example of a method that uses sensible heat is water.

Water has a large specific heat, is easy to handle, and above all, is extremely cheap.

In addition to water, gravel, crushed stone, and bricks are used.

However, if an attempt is made to store heat using sensible heat, the capacity and weight of the heat storage device will become considerably large.

Another disadvantage is that the temperature of the heat storage agent itself decreases in proportion to the release of heat.

On the other hand, examples of methods that utilize latent heat include methods that use inorganic hydrated salts and organic crystalline substances.

In principle, this method utilizes phase change phenomena such as melting that occur at a constant temperature, and the temperature drop of the heat storage agent due to heat release is small, and the latent heat of phase change such as melting is generally large, making it compact. can store heat.

The present invention focuses on a technology for storing heat by utilizing the latent heat of fusion of this inorganic hydrated salt, especially calcium chloride 6, which has a melting point near room temperature.
This invention relates to a technology for modifying water salt to make it suitable for use as a heat storage agent.

Calcium chloride hexahydrate is originally known as an inexpensive heat storage material, but it has two crystal structures with different latent heats of fusion and is corrosive.
It has the disadvantage that it exhibits a noticeable supercooling phenomenon.

When calcium chloride hexahydrate is gradually cooled from its molten state, it does not solidify (crystallize) or release heat even after the original phase change temperature of 29°C. This causes a practical inconvenience in that even if heat is stored, the heat cannot be extracted at a predetermined temperature.

Therefore, in order to use calcium chloride hexahydrate as a heat storage agent, it is important to suppress this supercooling phenomenon.

An object of the present invention is to prevent the above-mentioned supercooling phenomenon of calcium chloride hexahydrate, and to provide a heat storage agent composition that is inexpensive, has stable heat absorption and radiation properties, and has a high heat storage density.

In order to suppress the supercooling phenomenon of calcium chloride hexahydrate, the present inventors have diligently researched a nucleating agent that promotes the generation of crystal nuclei during the exothermic crystallization process of calcium chloride hexahydrate. They discovered a nucleating agent that is effective against calcium chloride 6 water temperature and completed the present invention.

That is, the gist of the present invention resides in a heat storage agent composition in which barium thiosulfate is added to calcium chloride hexahydrate.

The barium thiosulfate used in the present invention is barium thiosulfate monohydrate or anhydrous salt.

Barium thiosulfate monohydrate actually acts as a nucleating agent for calcium chloride hexahydrate, but even if an anhydrous salt of barium thiosulfate is added, the anhydrous salt will not react with the water in the heat storage agent. Since it can become barium thiosulfate monohydrate, it acts as a nucleating agent.

In the present invention, it is preferable to use barium thiosulfate powder.

The barium thiosulfate powder effectively acts as a nucleating agent when its surface comes into contact with calcium chloride hexahydrate.

Therefore, it is preferable that the barium thiosulfate used in the present invention has a smaller particle size because this promotes the formation of crystal nuclei of calcium chloride hexahydrate.

The preferred particle size of barium thiosulfate used in the present invention is 100 microns or less, more preferably 5 microns or less.
It is 0 micron or less.

The amount of barium thiosulfate used in the present invention depends on the particle size of barium thiosulfate.

That is, when the particle size of barium thiosulfate is small, the amount added may be small, and when the particle size becomes large, the amount added increases.

The preferred amount of barium thiosulfate used in the present invention depends on the particle size as described above, but is 0.01 parts by weight to 100 parts by weight of calcium chloride hexahydrate.
The amount is in the range of 20 parts by weight, more preferably in the range of 0.1 parts by weight to 10 parts by weight.As described above, the present invention adds barium thiosulfate to calcium chloride hexahydrate to exhibit a supercooling phenomenon. Although it provides a heat storage agent that is not
Depending on the temperature to which the heat storage agent is exposed, other nucleating agents such as copper powder or strontium chloride hexahydrate may also be used, or calcium chloride tetrahydrate or dihydrate or barium thiosulfate may be used in combination during melting. In order to prevent sedimentation and agglomeration, a thickener such as carboxymethyl cellulose or silicate fine powder may be added, or an additive such as a solidification heat dissipation temperature regulator may be added as appropriate.

Therefore, when the heat storage agent composition of the present invention is heated normally,
First, heat is accumulated as sensible heat in the solid phase state, and then when the solid state changes from the solid state to the liquid phase, a large amount of heat is accumulated as the latent heat of melting, and when the state completely changes to the liquid phase, heat is further accumulated as sensible heat. It accumulates.

When releasing heat, sensible heat is normally released from the high-temperature liquid phase state to the solidification temperature, and at the solidification temperature, the heat that was previously accumulated as latent heat of melting at that temperature is released without causing supercooling phenomenon. is released as latent heat of solidification (crystallization) over a long period of time, and when it completely changes to a solid phase, it releases heat as sensible heat while further lowering the temperature of the heat storage agent itself.

As mentioned above, the heat storage agent composition of the present invention is made by adding barium thiosulfate to calcium chloride hexahydrate, so it is inexpensive, has stable heat absorption and release performance without causing supercooling, and has heat storage properties. It has a high density.

The heat storage agent composition of the present invention has a melting point slightly higher than room temperature (2
9°C), so by combining it with solar heat or other heat sources, it can be used for residential equipment such as floor heating and wall heating, and for various other heat storage applications.

Examples of the present invention will be shown below.

Example 1 To 100 parts by weight of calcium chloride hexahydrate, 3 parts by weight of finely powdered silica (Aerosil #380; manufactured by Nippon Aerosi/L) was added and mixed with stirring to prepare an original sample.

Add 30 g of this original sample to barium thiosulfate monohydrate (particle size is approximately 20 microns at the middle position of the weight standard; measured by sedimentation method)
60mg was added and mixed by stirring, and the inner diameter was 18mm.
The sample was placed in a test tube with a length of 180 mm, a thermocouple was inserted into the center, and the upper end was sealed with a rubber stopper.

Then, this test tube was immersed in a constant temperature water bath at 45°C and sufficiently heated until the inside was melted and the temperature reached 45°C.

Next, this test tube was immersed in a constant temperature water bath at 15° C. to radiate heat, and the temperature change of the heat storage agent composition in the test tube was measured.

The heat release curve was as shown in 1 in FIG. 1, and it was confirmed that this heat storage agent composition solidified and released heat for a long time at 29° C. without causing supercooling.

Example 2 Barium thiosulfate was added to 30 g of the original sample prepared in Example 1.
A heat storage agent composition in which 1.5 g of aqueous salt (same as in Example 1) was added and stirred was subjected to measurement of temperature changes in exactly the same manner as in Example 1.

The heat release curve was as shown in 2 in FIG. 1, and it was confirmed that this heat storage agent composition solidified and released heat for a long time at 29° C. without causing supercooling.

Comparative Example The heat dissipation behavior of the original sample 301 prepared in Example 1 to which barium thiosulfate was not added was measured in exactly the same manner as in Example 1.

The heat release curve was as shown in 3 in Figure 1, and it was confirmed that this original sample was supercooled and almost no heat was released during solidification.

Example 3 A heat storage agent composition obtained by adding 60 g of barium thiosulfate monohydrate (same as in Example 1) to 30 g of calcium chloride hexahydrate and stirring the mixture was prepared in the same manner as in Example 1, and the temperature of its exothermic cooling was adjusted. Changes were measured.

The heat dissipation cooling curve of this heat storage agent composition was as shown in 4 in FIG. 2, and it was confirmed that solidification heat dissipation was performed at about 31° C. for a long period of time without causing supercooling.

Example 4 A heat storage agent composition prepared by adding 1.5 g of barium thiosulfate monohydrate (same as in Example 1) to 30 g of calcium chloride hexahydrate and stirring the mixture was subjected to heat radiation cooling in the same manner as in Example 1. The temperature change was measured.

The heat radiation cooling curve of this heat storage agent composition is as shown in 5 in FIG. 2, and this heat storage agent composition does not cause supercooling.
It was confirmed that solidification heat was dissipated for a long time at about 29°C.

Comparative Example 2 Calcium chloride hexahydrate 30 without added nucleating agent
The radiation cooling behavior of g was measured in the same manner as in Example 1.

The radiation cooling curve of this sample is as shown in 6 in Figure 2,
It was confirmed that this sample caused supercooling and was cooled down to ambient temperature with almost no solidification heat dissipation.

[Brief explanation of drawings]

FIGS. 1 and 2 are graphs showing the heat dissipation behavior of the heat storage agent composition of the present invention and a conventional heat storage agent composition to which barium thiosulfate is not added.

Claims (1)

[Claims] 1. A heat storage agent composition comprising calcium chloride hexahydrate and barium thiosulfate. 2. The heat storage agent composition according to claim 1, wherein the barium thiosulfate is barium thiosulfate monohydrate. 3. The heat storage agent composition according to claim 1 or 2, wherein the barium thiosulfate has a particle size of 100 microns or less. 4. The heat storage agent according to claim 1, 2 or 3, wherein barium thiosulfate is added in an amount of 0.01 to 20 parts by weight to 100 parts by weight of calcium chloride hexahydrate. Composition.